Process for treating animal fibers with ozone



United States Patent 3,149,906 PREECEflS FGR TREATING ANIMAL FEBERS'VETH QZQNE Waiter .l. Thorsen, El Cerrlto, Calif., assignor to theUnited States of America as represented by the Secretary of AgricultureN0 Drawing. Filed Mar. 11, 1963, Ser. No. 255,588 3 Qlairns. (Ci.8-l2fi) (Granted under Title 35, US. Code (1952), sec. 265) Anon-exclusive, irrevocable, royalty-free license in the invention hereindescribed, throughout the world for all purposes of the United StatesGovernment, with the power to grant sublicenses for such purposes, ishereby granted to the Government of the United States of America.

wool, mohair, and the like, with ozone in order to improve theirproperties. Further objects of the invention will be evident from thefollowing descrip tion wherein parts and percentages are by weightunless otherwise specified.

As a general proposition, the treatment of wool with ozone has beendescribed heretofore and has been suggested as a means of improving theshrinkage properties of the textile and increasing its affinity fordyes. Various investigators have explored the situation and haveadvocated different techniques for accomplishing their desired ends. Atypical procedure is that described in British Patent No. 242,027,November 5, 1925. In this process, wool is soaked in 5% ammonia solutionfor a few minutes, hydro-extracted (centrifuged) to remove excessliquid, then placed while damp in a chamber wherein it is exposed to aircontaining ozone in a concentration of about 1 part per 1000. Theprocess is exceedingly slow as evidenced by the fact that the patenteessuggest removing samples of the wool at intervals of a few hours to testthem for acidity. (if acid, the wool is again soaked in ammonia solutionprior to further ozone treatment.) The procedure of the British patent,termed the Zair process, was further investigated by Brown (Journal ofthe Society of Dyers and Colourists, vol. 44, pp. 230233, 1928), whoillustrates the long duration of the procedure, i.e. 5 to 20 hours, andsuggests that ties is attained when 15 hours. In addition to requiringlong processing times, the various prior procedures have involved suchdisadvantages as erratic and non-uniform results, decrease in abrasionresistance of the treated wool, and even loss of material duringprocessing by dissolving of a portion of the fibers. As a net result theozone treatment of wool has not met with commercial acceptance.

The process of the invention surmounts the difliculties above and leadsto the following particular advantages:

A primary item is that the process of the invention requires a briefperiod of time, that is, usually about 3 to 6 minutes and at most about10 minutes. Despite this short processing time, the treated fibersdisplay many improvements in their properties, namely:

The resistance of the fibers to felting and shrinking is markedlyimproved.

The treated fibers are treated) fibers.

The treated fibers take up dyes more rapidly than the untreated fibers.In addition, the fastness of the dyes to the ozone-treated wool isunchanged and fading resistance is equal to or better than with the dyeduntreated wool.

whiter than the original (un- The treated product displays increasedfiber forces; that is, the indivdual fibers cling more tenaciously thanis the case with the untreated material. in turn provides thesebenefits: Yarns can be spun to a higher count, that is, to finerdiameter or fewer fibers per cr ss-section. Yarns can be fabricated withless twist than from the untreated fibers, yet without any loss in yarntensile strength. (Yarns with less twist are especially desirable forfaricating garments as the products have improved wrinkle recovery).Finer yarns can be spun from the treated fibers and with greaterefllciency, e.g., with fewer breaks.

In addition to these advantages noted above, the treatment accordancewith the invention does not produce any degradative ellect so that thereis no detriment in what may be termed the purely mechanical propertiesof the material. Thus, there is no loss in tensile strength or abrasionresistance. In addition, the material retains its original hand so thatit is suitable for fabrication of garments of all kinds such as suits,skirts, shirts, etc.

in essence, the process of the invention involves contactiru the fibrousmaterial with a current of steam and ozone. Various conventional typesof textile-treating de- VlCES can be adapted for achieving the desiredcontact between the material and the steam-ozone mixture. Typically, forbatch operations one may provide a chamber supplied with perforatedshelves, a gas inlet, exhaust vent, and a discharge outlet for condensedwater. The fibrous material to be treated is laid on these shelves and astream of the steam-ozone mixture is directed into the chamber,preferably in such a manner that it actually passes through thematerial, or, more accurately, through the interstices betweenindividual fibrous elements. For continuous treatment of long lengths ofmaterial such as yarns, slivers, top, cloth, etc., the material can bethreaded over a series of perforated rollers supplied, through hollowshafts, with the steam-ozone mixture which then flows through thematerial as it passes over each roller.

Generally, the ozone is produced in a conventional device wherein oxygenis passed through an electrical system involving a high-voltage silentdischarge. The eflluent gas from this device contains, for example,about from 10 to 100 mg. of ozone per liter, depending on the circuitadjustments of the device. (The portion of this gas stream which is notozone is, of course, oxygen.) This gas stream is mixed with a stream ofsteam produced by a conventional steam generator. The relativeproportions of steam and ozone are so adjusted that the steam-ozonemixture has an ozone concentration of about 10 to 50 mg. per liter. Thetemperature at which the process of the invention is carried out may bevaried from about 60 to C. Temperature control of the treatment is mostreadily achieved by adjustment of the temperature of the steam-ozonestream. This in turn is readily controlled by adjustment of theproportions of steam and ozone which are combined. For example, byincreasing the proportion of steam in relation to the proportion ofozone coming from the ozone generator, the temperature of thesteam-ozone composite stream may be increased.

The time of contact between the fibrous material and the steam-ozonemixture may be varied depending on such conditions as the reactiontemperature, the concentration of ozone in the steam-ozone mixture, thetype of fibrous material being treated, and the degree of modificationof the fibrous material which is desired. example, an increase inreaction temperature or an incohesive to one another crease in ozoneconcentration will increase the speed of modification, In any particularcase, pilot trials may be conducted with the material to be treated,employing various conditions and testing the properties of the product.From such tests the appropriate conditions may be easily derived. Insuch trials, the shrinkage characteristics of the product may, forexample, be used as the criterion and the conditions of reactionselected so that the area shrinkage of the product (tested by a standardmethod) is markedly improved, i.e. reduced to at least one-half,preferably at least one-tenth, of that displayed by the starting(untreated) material. it is, of course, obvious that the process shouldnot be continued for such a long period as to cause degradation of thefibers. As noted above, the process of the invention is rapid so thateffective results are obtained in a matter of minutes, for example 2 to6 minutes, and in no case is the time of reaction more than 1.0 minutes.

Following the treatment with the steam-ozone mixture, the treatedmaterial may be acidified, for example, by dipping it into a bath ofdilute hydrochloric or sulphuric acid. Typically, this step isaccomplished by immersing the material in 0.1 N HCl for 1 to 3 minutes.This acidification acts to restore softness of hand to the treatedmaterial and to restore its original resistance to abrasion. Theacidification procedure is, however, optional and need not be applied ifsubsequent dyeing is planned as the acid or salt used in the dyebathaccomplishes the same purpose.

The process of the invention is applicable to animal fibrous materialssuch as wool and mohair and these materials may be in any of variousphysical forms, e.g. bulk fibers, slivers, roving, top, yarns, felts,woven textiles, knitted textiles, or even garments or garment parts.

The invention is further demonstrated by the following illustrativeexamples:

Example 1 Steam at 100 C. was mixed with a stream of ozone gas (50 mg.ozone per liter) issuing from an ozone generator. In the different runsthe proportions of the two initial streams (steam and ozone) were variedto provide difierent ozone concentrations in the composite stream.

In each run, steam-ozone mixture was introduced at a fiow rate of about0.1 cu. ft./rnin. into a chamber wherein it was forced through a sampleof wool cloth. In each case the time of treatment was 3 minutes.

Following the treatment, the treated wool samples were tested forshrinkage by the following test:

Standard shrinkage test.--The tests for shrinkage referred to below wereconducted in the following way: The wool samples were milled at 1700rpm. for 2 minutes at 40-42 C. in an Accelerotor with 0.5% sodium oleatesolution, using a liquor-to-wool ratio of 50 to 1. After this washingoperation the samples were measured to etermine their area and theshrinkage was calculated from the original area. With this washingmethod, samples of control (untreated) wool gave an area shrinkage of42%. The Accelerotor is described in the American Dyestuff Reporter,vol. 45, p. 685, Sept. 10, 1956.

' 4 The results obtained are summarized below:

Ozone con- Ternpercentration Area Run ature of in steamshrinktreatment,ozone mixage,*

C. ture, percent mgJliter Shrinkage of untreated wool was 42%.

Example 11 A sample of mohair top was treated as described above inExample I, run 4, Le. temperature C., time 3 minutes, ozoneconcentration 31.4 rug/liter. (The expression top is used in the tradeto designate the fiber product which has been produced by scouring theraw fleece, applying carding, combing and doubling to produce a thickstrand, about 1 /2 in diameter, of fibers in more or less parallelarrangement, i.e. with no twist. Top is thus the refined material whichis eventually treated by roving and spinning to make yarns.)

In order to test the cohesive forces between the individual fibers inthe treated top, the material was placed in a test instrument where itwas clamped between jaws spaced 8 apart and subjected to elongationWhile measuring the tensile force. Because of the wide spacing of thejaws, the results do not relate to tensile strength of individual fibersbut rather to the degree to which the fibers hold to another by cohesiveforces. It was found that the treated top broke at 6.5 lbs. whereasuntreated top broke at 1.5 lbs.

Having thus described the invention, what is claimed is:

1. A process for improving the properties of animal fibers selected fromthe group consisting of wool and mohair, in particular to improve theirshrinkage resistance, enhance their rate of dye absorption, and increasethe cohesive forces between individual fibers which comprises mixing astream of steam with a stream of ozone to provide a compositesteam-ozone stream having 'a temperature about from 60 to C. and anozone concentration about from 10 to 50 mg./liter, blowing saidcomposite stream through a mass of animal fibers for a period in therange about from 1 to 10 minutes, sufficient to attain said improvementsbut insufficient to cause degradation of the fibers.

2. The process of claim 1 wherein the animal fibers are wool.

3. The process of claim 1 wherein the animal fibers are mohair.

References Cited in the file of this patent UNITED STATES PATENTS1,628,484 Wilkinson May 10, 1927 1,825,178 Coghill Sept. 29, 19313,086,534 De Gorter et al Apr. 23, 1963 FOREIGN PATENTS 593,933 Sept. 2,1925 France

1. A PROCESS FOR IMPROVING THE PROPERTIES OF ANIMAL FIBERS SELECTED FROMTHE GROUP CONSISTING OF WOOL AND MOHAIR, IN PARTICULAR TO IMPROVE THEIRSHRINKAGE RESISTANCE, ENHANCE THEIR RATE OF DYE ABSORPTION, AND INCREASETHE COHESIVE FORCES BETWEEN INDIVIDUAL FIBERS WHICH COMPRISES MIXING ASTREAM OF STEAM WITH A SREAM OF OZONE TO PROVIDE A COMPOSITE STEAM-OZONESTREAM HAVING A TEMPERATURE ABOUT FROM 60 TO 95*C. AND AN OZONECONCENTRATION ABOUT 10 TO 50 MG./LITER, BLOWING SAID COMPOSITE STREAMTHROUGH A MASS OF ANIMAL FIBERS FOR A PERIOD IN THE RANGE ABOUT FROM 1TO 10 MINUTES, SUFFICIENT TO ATTAIN SAID IMPROVEMENTS BUT INSUFFICIENTTO CAUSE DEGRADATION OF THE FIBERS.